The penetration of ciclopirox through the nail plate is well documented by invitro studies utilizing cow horn and sheep and bovine nailplate. Studies of penetration in human finger and toe nail plates, both in vitro and in vivo, show similar penetration patterns. “There are limited data regarding the optimal corticosteroid concentration, duration and frequency of application”.
In vitro human C14 studies on excised onychomycotic nailplates showed drug penetration with 24hours and it was also noted that the more damaged the nailsurface by mycotic infection the greater the penetration.
The most clinically relevant report documents an invivo study of 5 healthy volunteers who applied the nail laquer daily to their toenails and removed it weekly according to the current treatment recommendations. Distal nail plate samples taken as early as day 7 showed uniform distribution of the drug within the nail plate at fungicidal concentrations. This persisted through the 45 days of application. Once the applications were stopped the concentrations declined dramatically by day 14 post application.
[JAAD supp October 2000 vol. 43 #4]